[Keyboard] Cradio keyboard (#14946)

Co-authored-by: Ryan <fauxpark@gmail.com>
Co-authored-by: filterpaper <filterpaper@localhost>

keyboards/cradio/readme.md

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+# Cradio keyboards
+
+![Cradio](https://github.com/davidphilipbarr/hypergolic/raw/main/hypergarlic/ht.png)
+
+Cradio are low-profile 34-key split-keyboards designed by [@davidphilipbarr](https://github.com/davidphilipbarr), with no diodes and direct micro-controller pin wiring.
+
+## Keyboard Info
+
+* Keyboard Maintainer: [davidphilipbarr](https://github.com/davidphilipbarr)
+* Hardware Supported:
+    * [Sweep](https://github.com/davidphilipbarr/Sweep)
+    * [Hypergarlic](https://github.com/davidphilipbarr/hypergolic/tree/main/hypergarlic)
+    * Variants of the same 34-key direct pin PCB
+* Hardware Availability: PCBs can be printed with gerber files from the repository
+
+Make examples for this keyboard (after setting up your build environment):
+
+    make cradio:default
+
+Firmware uses `EE_HANDS` split handedness by default. Each halve should be flashed once with the following:
+
+    make cradio:default:dfu-split-left
+    make cradio:default:dfu-split-right
+
+See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).
+
+## Bootloader
+
+Enter the bootloader in 3 ways:
+
+* **Bootmagic reset**: Hold down the top left key on the left half (or the top right right key on the right half) and plug in the controller on that side.
+* **Physical reset button**: Briefly press the reset button soldered on the PCB.
+* **Keycode in layout**: Press the key mapped to `RESET` if it is configured.